Modulation of d–d orbital interactions in Ti–Ni–N4 coordination introduces dynamic bonding for enhanced CO2 photoreduction

Photocatalytic CO₂ reduction using atomically dispersed catalysts holds significant potential for addressing global energy and environmental challenges. However, the influence of d–d orbital interactions between metal centers and coordinated atoms remains underexplored. Herein, nickel phthalocyanine is anchored to the metal-exposed crystal face of TiO₂, forming Ti–Ni–N₄ coordination. This configuration reveals that the axially coordinated Ti atoms serve as a novel electron channel with electron-donating ability, transferring electrons to the Ni center through d–d coupling. It is found that the dynamic adjustment of bond lengths and d-band centers in Ti–Ni bonding during CO₂ photoreduction process can effectively modulate the adsorption strengths of the Ni center for different intermediates. This leads to a significant enhancement in the photocatalytic performance for CO₂ reduction to CO without a sacrificial reagent, achieving an exceptional CO evolution rate of 378.5 μmol g⁻¹. Furthermore, the d–d coupling mediated by Ti–Ni–N₄ coordination increases the vacancy formation energy of active sites, preventing the leaching of Ni active centers. This study provides a strategy for the precise design of d–d orbital regulation and resistance to demetallization in photocatalysts for efficient CO₂ conversion.

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